In Finland, students erect da Vinci-designed bridge with ice

What a way to kick off the winter semester.

Before it opens to surefooted pedestrians, a car will be driven over this student-built frozen span to test its strength. (Rendering: Eindhoven University of Technology)

In the Russia-abutting Finnish region of North Karelia, a small army of scarf-swaddled students have just commenced work on what's to be the world’s longest bridge constructed from ice. (Well, not pure ice, but more on that in a bit). Spanning 213 feet, this frosty feat of engineering and design isn't just notable for being based on a bridge sketched out in a notebook by Leonardo da Vinci in 1502. It's also located in a highly ironic spot: near a quarry on private property owned by Tulikivi, the world’s leading manufacturer of heat-retaining soapstone fireplaces and sauna heaters.

Hey, at least the 150 intrepid souls involved in constructing the bridge during “severe conditions in shifts day and night for seven weeks” can count on there being a source of warmth to huddle up against at the end of a long and arduous day spent building an ice bridge in the frigid wilds of eastern Finland.

Said intrepid souls — hailing mostly from the Netherlands but also from several other European countries including Finland — will be working around the clock (“Long work disruptions are not an option because otherwise the equipment would freeze”) under the supervision of Arno Pronk, a researcher at the Eindhoven University of Technology (TU/e). Roel Koekkoek and Thijs van de Nieuwenhof will serve as the project's student co-managers.

Having previously completed two record-breaking ice dome projects in Finland including a glacial tribute to Gaudí’s Sagrada Família, the student team won’t be embarking on this new project — dubbed “Bridge in Ice” — with proverbial cold feet. The goal, once again, is to “investigate how far we can go with ice as a building material.”

And about that ice ...

Unlike a certain hotel-cum-art project in the Swedish Lapland that’s constructed anew each winter using chunks of freshly harvested ice, Bridge in Ice won’t actually be built using just solidified water. Rather, the bridge, like the previous ice domes, will be constructed from an ice composite material first developed during World War II by British inventor Geoffery Pyke to build a massive and indestructible aircraft carrier. Despite backing from Winston Churchill, the man-made iceberg-as-warship project never came to fruition.

Named pykrete, the slow-to-melt building material is predominately composed of frozen water with 2 percent paper fiber added for reinforcement. This small cellulose addition will add significant structural integrity to the bridge, rendering it three times stronger than a bridge built from pure ice and 20 times more pliable. In total, an anticipated 900 tons of pykrete will be used during the construction process.

Spanning a total of 213 feet with a 115-foot free span, Bridge In Ice will be the longest bridge to be constructed from ice. (Rendering: Eindhoven University of Technology)

When construction wraps up in mid-February (provided the weather cooperates), a car will be driven across the 16-foot-wide bridge to test its strength. Given that the car makes it across without issue, the span will then be opened to foot traffic as part of an annual ice festival hosted by the Finnish town of Juuka. When the festival concludes and springtime officially arrives, the paper fibers left behind after the bridge eventually melts away into nothing will be used as compost.

A bit more on the project’s innovative construction techniques:

Besides reinforced ice we use two more important techniques for constructing the Ice-structures. After mixing the fibers with water we pump the mixture through long tubes. By hand we spray layers of ice, just a couple of millimeters every time. We spray on big inflatable molds. These molds are positioned and inflated, secured to have a continuous air-pressure for as little deformation as possible. After the big balloons are totally covered with ice, and the structure has enough strength to stand on its own, we deflate the balloon and remove them. The result will be the largest single-span structure in ice ever realized.

And about that da Vinci connection …

Whereas the TU/e team’s previous ice-built structures were an igloo on steroids and a fanciful tribute to an iconic — and yet-to-be finished — basilica in Barcelona, Bridge in Ice follows a design first conceived by the Italian Renaissance’s most prolific inventor, portrait painter and cadaver tinkerer.

An early conceptual predecessor to the current Galata Bridge (itself now in its fifth iteration), the unrealized Leonardo da Vinci-designed stone footbridge was commissioned by Sultan Beyazid II of Constantinople to span the Bosporus, linking two sides of the ancient city now known as Istanbul via the Golden Horn. Believing that such a structure couldn't be built, the sultan ultimately rejected da Vinci’s nearly 800-foot design which would have been the longest bridge in the world had it been built. While certainly not one of da Vinci's most famous unrealized works, the bridge was never allowed to fade into total obscurity.

In recent years, there’s been renewed interest in the so-called “the Mona Lisa of bridges.” Numerous models have been built while in 2001, Norwegian artist Vebjoern Sand completed work on a modest span based on da Vinci’s original sketches. Located just outside of Oslo, the Leonardo Bridge Project stands as the first full-size realization of da Vinci’s design. Envisioned as a global public art project, it's also the first work of civil engineering based on a da Vinci sketch to be constructed.

Bridge in Ice — I'm thinking that "the da Vinci Cold" would be a fitting nickname — is the second full-size attempt at erecting the never-built structure and the first, obviously, to use a mix of sawdust, frozen water and student labor.

As mentioned, bundled-up students from universities across Europe are now descending on Juuka (current temp: minus 16 degrees Celsius) to join the core team from TU/e. A wide range of sponsoring companies along with the municipality of Juuka are also pitching in to help bring da Vinci's vision to life in ice.

Best of luck to all involved. Here's hoping they make the most noted ambidextrous polymath of the late 15th century/early 16th century proud!